Information Epidemics, Recommender Systems, and "The Crowd"

Can the Internet Spread Disease?

In May 2019, Dr. Müller-Walde, a psychiatrist at the Hannover Medical School in Germany, encountered the most bizarre series of cases in his career. Dozens of teenagers of similar age visited his clinic, presenting the same peculiar symptoms: sudden involuntary twitches and bursts of strange, contextually unrelated words during conversations or silence, such as "Pommes" (potatoes, fries) and "Du bist häßlich" (you are ugly). In ancient times, such people might have been thought to be possessed.

The cause of these symptoms was a popular YouTube channel called "Gewitter im Kopf," which is very popular among German youth. One of the co-founders of the channel, Jan, is a genuine sufferer of Tourette syndrome.

Jan and his friend Tim run the channel together, focusing on Jan's life with Tourette syndrome, which they affectionately name "Gisela." Their goal is to present this condition in an open, humorous, yet objective way to make it more understandable and relatable to everyone. Their videos not only share Jan's daily life but also explore the complications associated with Tourette syndrome.

Jan is a very polite person, but he occasionally blurts out odd phrases, adding a unique and engaging rhythm to the videos. Despite the uncontrollable forces within him, he strives to show a normal and dignified side in his videos, advocating for those with Tourette syndrome.

Dr. Müller-Walde discovered that the teenagers showing symptoms similar to Jan's appeared to be influenced by his videos, triggering their own underlying psychological issues.

Dr. Müller-Walde explained: "Although Tourette syndrome has a neurological basis related to physiological changes in areas like the basal ganglia of the brain, most of these teenagers actually suffer from a psychological condition known as functional movement disorder, which is entirely psychological. It's as if Jan's condition were a 'hardware failure,' while these teenagers have 'hardware' that is fine, but 'software' that malfunctions due to external stimuli."

When the doctor informed them that they did not have Tourette syndrome, the symptoms of some patients quickly disappeared, suggesting that they were consciously imitating Jan and subconsciously convinced themselves they had the same disorder, thereby reinforcing this psychological suggestion.

We are facing a new type of 'collective societal illness.' The outbreak of these pseudo-cases of Tourette syndrome indicates the emergence of a disease that spreads through social media networks, unrestricted by geography, a first in human history.

Information Feed Recommender Systems and Epidemics

Information flow is now a ubiquitous mode of information presentation. When we scroll through platforms like Instagram, Youtube, Tiktok, and Twitter every day, do we not also feel a degree of anxiety? The internet is rife with displays of wealth and heated debates that exhaust the spirit. This phenomenon is largely due to the presence of recommendation systems. These platforms share a common characteristic: they rely on us to keep scrolling, refreshing content, and as we encounter more 'interesting' information, our cognition and emotions are subtly influenced by these systems.

Facebook can be considered the progenitor of the information feed. Reflecting on my internship days at Facebook over a decade ago, my project was centered on personalized news feed recommendations. Before that, Facebook's feed operated on manually set rules, later shifting to a machine learning-based, data-driven approach, significantly enhancing user engagement but not yet achieving true personalization. My internship project focused on personalized information flow recommendations based on individual user preferences, a concept that later flourished on platforms like Toutiao, known elegantly as "Thousands of Faces."

In 2018, a major event shook the company. The data analytics firm Cambridge Analytica used Facebook's developer API to gather data, claiming it helped shape election strategies and influenced several major political events, including the 2016 US presidential election. This incident sparked a global discussion on data privacy and the responsibilities of social media platforms, forcing Facebook to change its data policies and tighten control over third-party access to user data. During the same period, the public influence of recommendation systems increasingly came under national scrutiny.

Whether these systems actually swayed the presidential election remains inconclusive, but it is undeniable that information flow recommendation systems have the capability to influence people's beliefs and worldviews. However, this influence is not unique to recommendation systems; all historical media tools have had this capability. The earliest missionaries spread information by foot and word, followed by various publications after the advent of the printing press, and then newspapers, radio, and television. Compared to these predecessors, recommendation systems have undoubtedly greatly enhanced the efficiency of influencing public opinion.

The Evolution of Information Spreading

As people receive information, they also unknowingly accept the views and emotions within it, which is the root of what we call information epidemics. In epidemiology, the source of infection, means of transmission, and susceptible hosts are the basic elements of disease transmission, typically founded on physiological bases. However, in the information age, cases like the pseudo-Tourette's syndrome outbreak in Germany, though not traditional physiological infectious diseases, still possess these three core elements.

Furthermore, if we broaden our perspective further, when we spread an idea, that idea can also spread like a contagion. This is what's known in the gray area of information as "fission-style" spreading, or "viral marketing."

From "The Crowd" to Susceptibility in the Information Age

In discussing the socio-psychological mechanisms of information dissemination, Gustave Le Bon's 1895 work "The Crowd" provides a profound perspective. The book delves deeply into group psychology and its influence on individual behavior. Le Bon posited that individuals within a crowd often lose the ability to think independently, becoming susceptible to emotional and impulsive influences, leading to irrational decisions. He highlighted anonymity, contagion, and suggestibility within the crowd, noting that crowd behavior is typically more extreme and unpredictable than that of individuals.

Connecting Le Bon's insights with modern information flow and recommendation systems reveals interesting parallels. Information flow recommendation systems propagate certain ideas or information among users through algorithms, akin to the emotional contagion Le Bon described. This can lead to rapid spread of opinions or behaviors across social networks, regardless of their objective correctness. Just as a crowd can make irrational decisions driven by emotion, users dependent on recommendation systems may not deeply analyze the content they are fed but are led by algorithmically designed "filter bubbles," thus limiting the diversity and breadth of perspectives. Moreover, the anonymity provided by online platforms can enhance the group behaviors described in "The Crowd," with people more likely to spread extreme or untrue information without feeling direct responsibility.

A key lesson from COVID-19 is that virtually everyone globally could be susceptible to a virus. On the informational and psychological levels, this susceptibility is arguably even more pronounced. In the real world, no disease can infect billions within a few hours; not the Black Death, not smallpox, not even COVID-19. Yet on the Internet, a piece of information can spread globally within hours, an occurrence that happens nearly every day.

This phenomenon redefines what it means to be susceptible in the information age: susceptibility is no longer limited to physiological factors but extends to psychological and emotional dimensions. The acceptance and speed of information dissemination by individuals or groups have become the new standards for measuring susceptibility. Information flow recommendation systems capitalize on this by using precise algorithms to enhance the contagion of information, influencing people's emotional responses and behavioral choices, thereby subtly altering societal dynamics.

The group behaviors discussed in "The Crowd" have found new interpretations and manifestations in today's world. In this digital and highly connected era, the power of information and its mechanisms of dissemination are more potent than ever, demanding that we pay greater attention to the quality and impact of information in both policymaking and personal decisions.